Metric thread,corrosion-resistant environmental protection.threaded inserts for wood. More Usage and Install: pre-drill a proper hole, screw-in with Screws Threaded Inserts. Fastener Connector Hex Socket Drive Threaded Insert Nuts For Wood Furniture Assortment. Applications: These furniture screws are suitable for furniture hardwood/ solid wood, for furniture combinations. Features of insert nut: These threaded inserts are inserted into a pre-drilled hole by screwing in, in that case the external protrusions bite into the wood, preventing the nut from either turning or pulling out. Material:Zinc alloy colour:Photo Color Package Contents: 40 * Hex socket (M4*8) 40 * Hex socket (M4*10) 30 * Hex socket (M5*10) 15 * Hex socket (M6*10) 20 * Hex socket (M6*15) 20 * Hex socket (M8*20) Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.